package cn.rongcloud.rtc.rn.beauty;

import android.opengl.GLES20;

/**
 * Helper class for handling OpenGL framebuffer with only color attachment and no depth or stencil
 * buffer. Intended for simple tasks such as texture copy, texture downscaling, and texture color
 * conversion.
 */
// TODO(magjed): Add unittests for this class.
public class GlTextureFrameBuffer {
    private final int frameBufferId;
    private final int textureId;
    private final int pixelFormat;
    private int width;
    private int height;

    /**
     * Generate texture and framebuffer resources. An EGLContext must be bound on the current thread
     * when calling this function. The framebuffer is not complete until setSize() is called.
     */
    public GlTextureFrameBuffer(int pixelFormat) {
        switch (pixelFormat) {
            case GLES20.GL_LUMINANCE:
            case GLES20.GL_RGB:
            case GLES20.GL_RGBA:
                this.pixelFormat = pixelFormat;
                break;
            default:
                throw new IllegalArgumentException("Invalid pixel format: " + pixelFormat);
        }

        // Create texture.
        textureId = GlUtil.generateTexture(GLES20.GL_TEXTURE_2D);
        this.width = 0;
        this.height = 0;

        // Create framebuffer object.
        final int frameBuffers[] = new int[1];
        GLES20.glGenFramebuffers(1, frameBuffers, 0);
        frameBufferId = frameBuffers[0];
    }

    /**
     * (Re)allocate texture. Will do nothing if the requested size equals the current size. An
     * EGLContext must be bound on the current thread when calling this function. Must be called at
     * least once before using the framebuffer. May be called multiple times to change size.
     */
    public void setSize(int width, int height) {
        if (width == 0 || height == 0) {
            throw new IllegalArgumentException("Invalid size: " + width + "x" + height);
        }
        if (width == this.width && height == this.height) {
            return;
        }
        this.width = width;
        this.height = height;

        // Allocate texture.
        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);
        GLES20.glTexImage2D(
                GLES20.GL_TEXTURE_2D,
                0,
                pixelFormat,
                width,
                height,
                0,
                pixelFormat,
                GLES20.GL_UNSIGNED_BYTE,
                null);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
        GlUtil.checkNoGLES2Error("GlTextureFrameBuffer setSize");

        // Attach the texture to the framebuffer as color attachment.
        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, frameBufferId);
        GLES20.glFramebufferTexture2D(
                GLES20.GL_FRAMEBUFFER,
                GLES20.GL_COLOR_ATTACHMENT0,
                GLES20.GL_TEXTURE_2D,
                textureId,
                0);

        // Check that the framebuffer is in a good state.
        final int status = GLES20.glCheckFramebufferStatus(GLES20.GL_FRAMEBUFFER);
        if (status != GLES20.GL_FRAMEBUFFER_COMPLETE) {
            throw new IllegalStateException("Framebuffer not complete, status: " + status);
        }

        GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
    }

    public int getWidth() {
        return width;
    }

    public int getHeight() {
        return height;
    }

    public int getFrameBufferId() {
        return frameBufferId;
    }

    public int getTextureId() {
        return textureId;
    }

    /**
     * Release texture and framebuffer. An EGLContext must be bound on the current thread when
     * calling this function. This object should not be used after this call.
     */
    public void release() {
        GLES20.glDeleteTextures(1, new int[]{textureId}, 0);
        GLES20.glDeleteFramebuffers(1, new int[]{frameBufferId}, 0);
        width = 0;
        height = 0;
    }
}
